Printing apparatus



Dec. 29, 1959 J. H. REED m PRINTING APPARATUS 4 Sheets-Sheet 1 Filed Aug. 20, 1956 I.- Fl lllL r IN VEN TOR.

James H Reeqm th mww w ullllllllllll lll I;

t. w um". fi 9 mm a m 8 o mm Hi5 A T TORNEYS Dec. 29, 1959 REED m 2,918,866

' PRINTING APPARATUS Filed Aug. 20, 1956 4 Sheets-Sheet 2 INVENTOR. James H. ReedJH' QMZWW HAS A TORNEYS Dec. 29, 1959 J. H. REED Ill 2,918,866

PRINTING APPARATUS 4 Sheets-Sheet 3 Filed Aug. 20, 1956 25 ,.25 4 4 .AL; )1] k \0 A 4] F Y r INVENTOR. James H. Reed,lZI

A T TORNE YS Dec. 29, 1959 REED m 2,918,866

PRINTING APPARATUS Filed Aug. 20, 1956 4 Sheets-Sheet 4 36 27 2s 4 I8 38 7 1Q l an I L I o o O O In o o 1 8 4o 35 4;

INVENTOR. James H Reed,.lZZ

H/S ATTORNEYS Unit t s OT This invention relates to printingapparatus' and more" particularly to screen printing machines in which apririt-' ing composition is forced through a" screen onto stock to be printed by a squeegee or similar element mountedupon a stand as the screen is moved acrossand in engage ment with the squeegee while simultaneously; the'stock is also moved in the same direction as the screen and adjacent the screen whereby printingcomposition is 'de-" posited onto the stock. The screen, which may be' wire 'mesh. or a fabric made-from various kinds of 'fibers; is; stretched tightly upon a frame and has on'itastencil' comprising a design, printed matter or a' combination thereof and formed by rendering parts of the s'creen'im pervious to passage of the-printing composition-therethrough.v The stock to be'printed isplaced upon a:b'ed' which-is moved to a positionbeneath the screen where the squeegee engages the screena'nd where the screen either contacts the'stock or is a short distance above the stock. Generally, the stock is'p'aper, cardboard: plastic or metal sheets.

My machine is particularly well'adapted for the socalled hot color process of printing thermoplasti'c'inks.

In the hot color process, the ink dries immediately as it isv printed on the stock or material which; therefore, comes oif the press perfectly dry, ready for delivery or for additional printing. The color or printing composition is heated before being fed onto ascreen to impart a proper viscosityto the printing composition sothat it may be easily appliedto thestock without-fouling" or clogging the screen.

ejected from the press.

l-Ieretofore the use of these thermoplastic inkshas been limited to the printing'of relatively crude-work, pri-" marily because of the difficultyof'separatingthe'screenfrom the stock after the ink hasbeend'eposited-oii thestock. Another difficulty has been the preheating of'thepaper stock by the hot screen and the heating-of the ink by the screen after printing so that the ink hasnot dried asquickly as desired. I have invented a screen printing machine especially suited for printing with thermoplastic My machine brings the stock and the screen together so that'th'ey contact eachother along a narrow areaextending across theinks which solves these difficulties.

width of the stock, which area is so small as to be-almost a line :contact. The result is that'thestock' is not heated The screen is heated to maintainthe printing composition in a molten state and" whenthe composition is applied' to the:relatively'cooler' printing;- surface of the stock, it instantly solidifies into a thin",-' perfectly dry film before the stock' canbe removed or' parallel guideways 6 shaped rail 8-and guideway 6, a substantially-fiat rail 9.: The. ends of the curved guidewayso and 7 are secured to crossangle-bars'lllz p The frame z travels along a pair of substantially flat-- parallel T guideways 11 and by being close to the-hot screen'before printing and the stock is separated from the screen im'mediatelyafter the ink has been forced through the' screen onto the stock.

Thus, fine printing work can be done with thermoplastic inks with all the advantages ofrapid-drying;

Myv machine comprises two-members, one'being a bed" adapted for supporting stock to be'printedand the other being a frame which houses the screen and upon which thescr'eedistautly stretched. "Oneof the two members 2,918,866 Patented Dec. 2 9, 1959 2' is longitudinally curved and the other is substantially'fiati I employ a stand which has guideways mounted thereon which guideways extend longitudinally of the" stand.- S om'e'of the guideways are mounting thecurved one of' the two members ari'cl with the" flat guideways mounting the substantially flatme'rn ber ofthe two members. Both members are adaptedto travel back and forth upon theirrespective guideways and are moved there'along by driving means connected to one"- of the two members.

ber simultaneously moves along its guideways in the same direction. The curved guideways are I positioned on the stand relativeto the fiat guideways so that at least aportion' of the curved guideways is adjacent to the flat guideways and so that the path of travel of the flat member along its guideways is substantially tangentto" the path of travel of the curved-member along. its guide wa'ys; Mounted upon the stand substantially at the pointoftangency betweenthe paths'oftravel of the curved" me'r'nberand of the flat member isa mechanism for'forc' inga'printing. composition through" the screen ontoxthe. stock positioned upon the bed as'the' frame and bed travel,

along their respective guideways.

In the accompanying drawings I have shown a preferred:ernbodiment of my. invention in which:

Figure lis aside elevation view'of my invention;

Figure 2 is-a sideelevationview similar to Figure 1" showing the frame and bed":

with some parts omitted and at-the end of a'return stroke;

Figure 3-is a section view along the-line IlI'IIl of.

Figure l but on a larger scale than Figure 1;

Figure 4 is aschematic diagram showing how I con-' nect the frame-tothe bed and also'showing means for? preventingthestock-from sticking to the screen,

Figures 5 and 6 squeegee into engagement with the screen for the mechanism; I p

Figure 7 is a plan view of theframe-andscreen; Figure 8 Figure 7;' and Figure 9 is a diagramshowing the curvature of the bed-andof the guideways alongiwhich the bed'travels.

As shown in Figures 1,-2--and- 3, my

reservoir 5 for holding printing composition with-both theframe and the bed adaptedfor-traveling backand; forth along guidewayssecured to the frame structure and extending longitudinally thereof. a The bed 3 travels along a pair of longitudinally curved, and 7 witlrguide-way 7 having av? v v 12,'each ofxwhich has. a fiat rail 13.- Both ends of flat. guideways 11 and'12 fare se-' cured to stand uprights 14. I

A drive mechanism- 15 mounted upon-a baselfi secured I to uprights 14 of the stand'moves both the frame and the bed simultaneously in' 'the same direction back and forth along their respective guideways. The n'iechanismcompr1sesamotor17 which drivesapair of face plates 18 one located oneach side of the stand 1 and which areike yed upon'shafts19. Motor 17 drives the,shafts I through a clutch and brake mechanism 20 and through,-.

a right angle drive 21 connected to the shafts. To in d I longitudinally curved and the others are substantially flat with the curved guideways I Means connect the two members together so that as the one connected to th'e driving means travels along its guideways, the other mem show mechanism for lowering the during theta printing-stroke and raising it up off-of the screen duringthe return stroke with Figure 5--also-showing a-carn way.

is-asection view along the line VHF-VIII of apparatus com-' prises a stand l-made from-angle bars. Mounted-uponthe stand are a frame 2, a bed -3, a squeegee 4;anda-v part a reciprocating motion to both the frame and the bed along their respective guideways, I employ, on each side of the stand, a linkage 22 which connects the driven face plates 18 to the bed 3.

So that the frame 2 travels simultaneously in the same direction along its guideways as the bed, I employ two pairs of bands 23 (Figure 4) made from flexible metal strip and adapted to connect the frame 2 to the bed 3 whereby both the bed and the frame travel together as previously described. Both pairs of bands are similarly arranged between the frame and the bed with one pair of bands being disposed along one side of the frame and bed and the other pair along the opposite side of the frame and bed. As to each pair of bands, each band is diagonally disposed between the frame and the bed with one band occupying one diagonal therebetween and the other band, the other diagonal. Each band has one end secured to one end of the frame and the other end secured to the opposite end of the bed.

The linkage 22 comprises a connecting lever 24 having one end pivotally joined to face plate 18 at a point adjacent its periphery and having its other end pivotally joined to a vertically disposed push-pull rod 25 at a point near its lower end. The lower end of the pushpull rod 25 is pivoted to bottom angle bar 26 of the stand and the upper end of the push-pull rod is pivotally connected to one end of a cross lever 27. The other end of the cross lever is pivotally joined to bed 3.

Rotation of face plate 18 imparts a reciprocating motion to the push-pull rod 25 connected to the face plate through the connecting lever 24. The reciprocating motion of the push-pull rod moves both the bed and the frame connected thereto by the bands 23 back and forth along their respective guideways.

Referring to Figure 1, which shows my apparatus in midstroke, as face plate 18 turns in a clockwise direc tion, it, acting through connecting lever 24 pushes the push-pull rod to the left which, in turn, causes the frame and bed to travel to the left. Pushing the bed and frame to the left is a part of the return stroke of the apparatus to the starting position shown in Figure 2. As the face plate 18 continues to turn in a clockwise direction, it, acting through connecting lever 24 pulls push-pull rod 25 to the right, thereby moving the bed and frame from the position shown in Figure 2 to the right along their respective guideways. Travel of both the bed and frame to the right constitutes the printing stroke of my apparatus.

The bed 3 has a framework 28 made from angles 29 which form both the sides and end of the bed. The framework supports a registration board 30 which supports the stock 32 to be printed such as paper, cardboard, plastic or metal sheets.

As shown in Figures 1 and 9, the bed has a longitudinal curvature which is slightly different from that of the guideways along which it travels for a purpose later explained.

The angles 29 which form the bed framework support rollers 33 and 34 adapted for travel along the V-shaped and flat rails of the curved guideways 6 and 7. In Figure 3, rollers 33 of which there are two on the same side of the bed and one at each end thereof which have a V-shaped contour whereby they fit upon the V-shaped rail. Rollers 34 of which there are two, both on the same side of the bed 3 and one at each end thereof, have a fiat working surface for engaging the fiat faced rail 9.

The frame 2 carries a screen 35 through which printing composition is forced down onto stock positioned upon the registration board. The frame 2 comprises a rectangle 36 made from side angle members 37 and crossbars 39. Each of the side members 37 of the rectangle support two rollers 38, one on each end which are adapted to travel along rails 13 of the guideways 11 and 12. Crossbars 39 connected to the rectangle 36 in combination with mounting tabs 40 provide a floating bar support for the screen 35, preferably made from stainless steel cloth. Stainless steel cloth is desirable for the screen because it has a relatively high electrical resistance which enables the screen to serve as its own heating element. Generally, mesh 188 stainless steel cloth woven from .0019 wire provides fine enough detail for all practical requirements, but finer mesh up to 230 may be used where better detail is desired.

Referring to Figure 7, angle bar frame 41 supported by dielectric mounting tabs 40 from the crossbars 39 carries the screen 35 with the sides of the stainless steel cloth machine stitched to intervening strips 42 of light canvas or duck which, in turn, is crimped into strips 43 of galvanized angle for drawing the screen taut upon the angle bar frame 41 by adjustment of bolts 44. At the ends of the screen, the stainless steel cloth is soldered to crimped galvanized angle strips 42 which are, in turn, bolted to aluminum bus bars 45 (Figure 8). These aluminum bus bars deliver a low voltage, high amperage heating current to the screen from a power source connected to the bus bars through cables 46 joined to straps 47 which are, in turn, soldered to the bus bars 45. Preferably, the angle bar frame is made of aluminum since the thermal expansion of aluminum is slightly greater than that of stainless steel, thus not only maintaining, but slightly increasing the tautness of the screen when it is heated. A rubber grommet 48 located around the perimeter of the bottom inside edge of the angle bar frame over which the screen is stretched insulates the screen from this frame. For good results, it is desirable that the screen be held at a relatively finely controlled temperature slightly above the melting point of the printing composition employed. To so control the temperature of the screen, I pass a low voltage, high amperage current through the screen. The preferred printing temperature is obtained by setting a current regulator within 5 amperes above the current required to melt the composition. At such a setting of the screen current, the thermoplastic printing composition has the proper viscosity to effect sharp and clear printings when forced through the screen by the squeegee. The desired current and voltage are obtained from a conventional control (not shown) mounted beneath the bed 3 on the stand 1.

As shown in Figure l, the curved guideways 6 and 7 are positioned upon the stand below the flat guideways 11 and 12 with the flat guideways being parallel to a tangent at the midpoint of the curved guideways. At the midpoint of the curved guideways, the flat guideways are so positioned upon the stand 1 that the screen is a small distance directly above stock mounted upon the registra' tion board 30 and at this midpoint the stock than at any other point of the frame and of the bed. Thus the frame 2 upon its guideways is to a tangent to the path of travel guideways with there being a point approximating tangency between the two paths of travel of the frame and of the bed. At this point, I mount upon the stand and above the screen the squeegee 4 which engages the screen along the guideways the path of travel of substantially parallel 35 as it travels along its guideways and forces printing v composition from reservoir 5, also mounted upon the stand, above the screen and just to the left of the squeegee (Figure 1 through the screen and down onto stock supported upon the bed.

With the squeegee mounted above the screen at the 1 point approximating tangency between the paths of travel of the frame and the bed carrying the stock and with the frame and bed traveling simultaneously to the right, viewing Figure 1, along their respective guideways, the bed presents a portion of the stock to the portion of the screen engaged by the squeegee and directly therebeneath, whereby that portion of the screen engaged by the squeev gee is printed upon the stock. As

the screen is closer to 7 of the bed 3 upon its the frame and bed. continue to travel to the right, succeeding portions of both a pifssee the screen and stock reach the point beneath the squeegee where succeeding portions of the screen: are printed upon the succeeding, portions of the stock- Since, thecur'ved. guideways slope away from the point of tangericy on, both sides thereof, the printing area is confined, to a narrowg line extending across the screen.

The squeegee 4 is mounted upon an angle member 49 positioned transversely of' the stand and rigidly secured thereto. The squeegee 4? extends substantially across, the. width of the screen 35 which, it engages when. the frame 2 travels from left to right (viewing Figure l). for the, printing stroke. I Referringto Figures 5 and 6, 1 set the squeegee 4 in a. holder 50 which is mounted between two vertical posts 51 rigidly secured to bracket 52 connected to the, angleifriember 49'. Each post has a vertical slot53 into which rollers 54, extending from the squeegee holder, fit so th t the, squeegee and its holder maybe lowered down into engagement'with the screen and raised up off of the. screen as" the rollers travel the. slots in the vertical, posts.

Figures 5 and 6 show a linkage mechanismwhich, automatieally lowers the squeegee down into engagementwith the screen at the beginning of, the printing stroke andv maintains the squeegeein' contactjwith the screen throughout the printing stroke. This mechanism also automati cally raises the squeegee up off of the screen at the start of the return stroke and hol'cl'sit up off of the-screen. throughout the return stroke. The linkage inechanisnnof which there is one on each side of the angle member 49;

supporting the squeegee, comprises a vertically disposed curved arm 55 having its upper end connectedito' aprojection 56" of thesqueegec holder 50 and it's'lower t'a'ild .'piv'ot. ally joined to an arm 57 of an L-shaped lever 58,. The other arm 59' of the lever 58 carries aca'rn'rol1er60 and, the L-shaped' lever is pivotally mounted at the intersection of arms57 and 59 upon a gusset plate 61 secured to the angle member.

Asshown in Figures 3' and. 5', I provide a cam-way 62. on each side member 37' of rectangle 36ofthe frame for the cam roller 60. Thecam way hasv a depression 63 adjacent each end thereof which cooperates withthe linkage mechanism for' lowering the squeegee'down into engagement with. the screen for the printing'stroke' orfor raisingthe squeegee up. off of the screen for the return stroke. Figure 6 shows the position of the cam roller and: squeegee during the'returnfstroke with the squeegee raised up off of the screen and Figure 5 shows'the position of 'the camroller and, squeegee duringthe printing.

SU'Oke Lowering of the'squeeg'ee into contact with the, screen,

occurs-when, withthe-camroller 60 invdepression63'a, the.

frame 2' starts to travel to the right, viewingFigurel. whereupon, the lever 58 pivotsin a counterclockwise direction, thereby; causing curved arm 55' to pull the squeegee and its holder downwardly into engagementwith the screen 35 with the rollers 54 of the holder rid. ingjin'the vertical slots of the posts 51.

When the carrier reaches the, right-hand end' of guide- 7 ways 11 and 12,'the cam roller there enters depression 63b -and-upon start of travel of the frame to the left, the cam roller, 'inmoving up out of depression 631), causeslever 58 to pivot in a clockwise direction. Aslever 58 pivots in a' clockwise direction; arm 57' thereof pushesv curved arm 55 upwardly, thereby raising the. squeegee. up' out of contact with' thescreen for the return fstroke with-the squeegee holder moving upwardly on rollers 54 in the'vertical slots of" the posts.

The reservoir 5 for the printing composition has ,con-

ventional electric resistance heating elements (not shown) embodied therein for heating the thermoplastic printing composition to a desired temperature." 7

. Forcontinuous. feeding of printing "composition to the screen during each printing stroke, I use a' control mechanism which comprises a solenoid-6'4 energizedby 1 a, cable 65 connected to an electric power source (not is secured to the lower end of stem 68 whose upper end.

is joinedto one end of lever 69. The other end of lever 69 is connected to armature 70 of the solenoid 64 with the center of the lever pivoted upon thereser'voir 5 so. that the valve rod 66 seats in the bottom of'the reservoir 5 when armature 70 of the solenoid 64 is raised by a spring 71. The solenoid armature 70- raises the valve rod 66 from the bottom opening of the reservoir when the solenoid is energized. p 7 Operation of the solenoid results from engagement of switch 72 mounted upon reservoir 5 with stops 73 and- 74 mounted uponv frame 2; Engagement of. the switch 72 with stop. 73 energizes the solenoid: 64 to raise the valve rod and openvthe reservoir on the printing stroke and, engagement of the. switch 72) with the stop 74 cuts off the supply of vcurrent to the solenoid whereupon the spring 71 lowers the valve rod and closes the reservoir.

Preferably, I employ my apparatus in off-contact printing but it may also be employedincontact printing. For off-contact printing itis essential that when'thesqueegee engages the center. of the screen 35,. the screen is not forced down into contact with the stock. Since the screen has a certain amount of give, particularly at its center part, when the squeegee, in contact with the screen during a printing stroke, reaches the center part of the screen, it depresses, the center part a greater amount than it depresses other parts of the screen (Figure 9). To compensate for this greater amount of depression at the center of the screen and to insure oif-contact-printing, I make the radius of-"curvature of the guideways 6 and '7 of the bed different from the radius of curvature of the bed itself. As shown inFigure. 9, the curvature of the bed is less than that of the guideways so that'when the carrier is atthe center of the bed and frame and the squeegee is in contact with the screen, the screen, while.

depressed, is out of contact with the stock 32. I have obtained good results in off-contact printing with a taut screen when average. clearance is from screen to surface of the stock.

To compensate for the greater. amount of depression in the center of the screen and to insure that the squeegee continuously engages the screen with a uniform pressure throughout the printing stroke, I providea dip in the center part of the cam way 62. along. which-the cam roller 60'travels (Figure 5). a

To prevent the'stock' to be printed from sticking; or-

adhering to the 1 screenafterthe printing stroke and. to

provide easy and efficient peeling. awayof the stock :from the screen and delivery of the stock from the registration board to a receptacle, I employ a-pair of fabric straps 75, one located along each side of the hed andadapted to'engage a side of the stock disposed upon the registration board. One end of each strap. is affixed to the lefthand end of the frame 2 and the other end to an end ofa conventional spring wind-up 76, onefor each strap mounted uponthe right-hand end of the stand. and below the flat guideways (Figure 4).

After a sheet of stock has been fed onto theregistration board and the-board has moved towards the squeegee in the printing stroke, each strap engages the leading end of one side of the stock and holds it down "upon the.

registration board. During travel of the bed toward the squeegee, the frame has also traveled towards this point and the straps engage successive portions of the side' of" the stock. The spring wind-up maintains the strap under a light tension throughout the printing stroke and takes up. slack in the strap as the frame moves towardsthe right. ,In' taking up theslack, the wind-up shortens the length of the strap with advancement of the frame' along its guideways. The strap 75 thus preventsthe'zstock*fronrt 7 sticking to the screen during the printing stroke. For the return stroke, the spring wind-up 76 pays out the strap as the frame moves along its guideways to its starting position.

A cam operated suction cup 77 pivotally mounted upon a bracket 78 adjacent the right-hand end of the stand 1 and below the fiat guideways 11 and 12 engages the stock disposed upon the registration board after printing and removes it therefrom. Upon removal of the stock from the registration board, the suction cup delivers it to a receptacle 79. The suction cup is moved to the position shown in Figure 2 upon the return stroke of the apparatus by a cam mechanism (not shown) actuated by the frame, whereby the cup 77 is normal to the surface of the stock and there engages it. When the cup 77 engages the stock carried by the registration board, the cam mechanism actuated by the frame, turns the cup in a counterclockwise direction to the position shown in Figure 1. Movement of the cup from the position shown in Figure 2 to the position shown in Figure l ejects a sheet of stock from the board and delivers it to the receptacle 79.

Operation of my apparatus, which is completely automatic, comprises the following steps:

(1) With the frame and bed in the position shown in Figure 2, a conventional stock feeding apparatus, not shown, delivers a single sheet to the registration board and positions it thereupon.

(2) Immediately after a sheet of stock is delivered to the board, the driving mechanism 15 moves both the bed carrying the stock and the frame along their respective guideways towards the squeegee mounted astride the screen.

(3) Just before the leading end of the stock reaches the squeegee, the stop 73 engages the switch 72 which actuates solenoid 64 to raise valve rod 66 up from its seat at the bottom of the reservoir whereby printing composition is fed down onto the screen.

(4) The squeegee engages the screen and forces the printing composition therethrough onto the stock and as the screen and bed continue their travel along their respective guideways, successive portions of the screen are printed upon successive portions of the sheet.

(5) Upon completion of the printing stroke, the stop 74 engages switch 72, thus immediately shutting off power to the solenoid 64 and permitting spring 71 to force valve rod 66 into the bottom opening of the reservoir 5, thereby shutting ofi delivery of printing composition to the screen.

(6) A suction cup engages the printed sheet and ejects it from the registration board and drops it into the receptacle 79.

(7) The driving means then returns both the frame and the bed to their starting positions and the printing operation is repeated.

My apparatus has important features which make it highly desirable for those printing posters, magazine covers, plastic and metal sheets, and any other material where one or more colors are used. Specifically, my apparatus makes possible a simple, easy and completely automatic printing of multicolored work which does not require a wait for the printed matter to dry or does not require use of auxiliary equipment for drying and hardening the printed matter. Thus my apparatus has a high rate of production while at the same time, producing clear and distinct figures, designs and letters. In addition, it has a rugged and simple structure which requires relatively little maintenance and is economical to manufacture and operate. Furthermore, my apparatus is adapted for both off-contact printing and contact printmg.

While a certain preferred embodiment of my invention has been shown and described, it will be understood that it may be otherwise embodied within the scope of the appended claims.

I claim:

1. Screen printing apparatus comprising two members, one being a bed adapted for supporting stock to be printed and the other being a frame, a screen housed in said frame, the bed member being longitudinally curved and the frame member being substantially flat, longitudinally extending guideways, some of said guideways being longitudinally curved and the other of said guideways being substantially flat, the bed member being mounted for movement upon said longitudinally curved guideways and being adapted to travel back and forth thereupon, the frame member being mounted for movement upon said substantially fiat guideways and being adapted to travel back and forth thereupon, driving means for moving the two members back and forth along their guideways so that the two members move simultaneously along their guideways in the same direction, said curved guideways being positioned relative to said flat guideways so that at least a portion of said curved guideways is adjacent to said flat guideways and so that the path of travel of said substantially flat member alongv its guideways is parallel to a tangent to the path of travel of said curved member along its guideways, and so that said paths of travel of said curved member and of said flat member have approximately a point of tangency therebetween, means mounted substantially at said point of tangency between the paths of travel of said curved member and said flat member for forcing a printing composition through said screen onto said stock as said frame and said bed travel their respective guideways, and means for heating said screen in said frame member.

2. The apparatus of claim 1 characterized by the curved guideways having a different longitudinal curvature than that of said curved member. I

3. Printing apparatus of claim 1 characterized by said apparatus having means for preventing said stock to be printed from sticking to said screen, said means being connected to one of said two members and to said stand and being adapted to engage said bed, and being adapted to be wound up and payed out in accordance with the travel of the member to which it is connected.

4. Apparatus of claim 1 characterized by the curved guideways having a different longitudinal curvature than that of said curved member and said apparatus having a means for preventing said stock to be printed from sticking to said screen, said means being connected to one of said two members and to said stand and being adapted to engage said stock supported on said bed and being adapted to be wound up and payed out in accordance with travel of the member to which it is connected.

5. Apparatus of claim 1 characterized by said apparatus having cooperating means connected to said printing composition forcing means and mounted upon said stand for lowering said printing composition forcing means down into engagement with said screen when said two members are driven in one direction along said guideways and for raising said printing composition forcing means up off of engagement with said screen when said two members are driven in the opposite direction along their respective guideways.

6. The apparatus of claim 1 characterized by the curved guideways having a different longitudinal curvature than that of said curved member, and having cooperating means connected to said printing composition forcing means and mounted upon said stand for lowering said printing composition forcing means down into engagement with said screen when said two members are driven in one direction along said guideways and for raising said printing composition forcing means up off of engagement with said screen when said two members are driven in the opposite direction along their respective guideways.

7. Printing apparatus as described in claim I, in which the driving means comprises a push-pull rod pivotally secured at one of its ends to one of said two members by a cross lever and pivotally mounted at its other end at a point on the concave side of the curved guideway but away from the guideway and adjacent the center lengthwise of the machine, a crank, and a connecting lever pivotally connecting the crank and the first lever and a motor for rotating the crank.

References Cited in the file of this patent UNITED STATES PATENTS Bland July Johnston et al. Nov. Williams Jan. Welsh Jan. Ragan Nov. 

